1. Field of the Invention
This invention relates to novel filaments and yarns for carpets, upholstery and other applications, the spinneret and method for their production and carpets manufactured therefrom. The filaments of the invention are solid multi-lobal filaments of complex convex-concave surface contour possessing low luster, low moment of inertia, high color intensity upon dyeing, and high covering power. Carpets manufactured therefrom possess low luster, soft hand, and high body suitable for premium residential application.
2. Description of the Related Art
A large number of the carpets used in residences in the United States are known as cut pile carpets. In their manufacture, pile yarn is inserted into a backing material as loops. The loops are cut to form vertical tufts and then sheared. Cut-pile carpet is customarily produced from staple yarns or bulked continuous filament yarn. Bulked (texturized or crimped) continuous filament nylon yarn is produced according to various conventional methods. Twisting, entangling, or direct cabling may be utilized in various processes. Multiple ends of twist set yarns are tufted into cut pile carpet and conventionally finished to obtain the desired carpet product.
The perceived value of carpets is dependent upon several factors including carpet body, luster, color intensity, and increasingly softness of hand. It is known that carpet body can be improved by increasing the face weight of the carpet or by increasing the crimp imposed on the face fiber. However, carpet face weight is directly proportional to the carpet""s total production cost. Furthermore, highly crimped fiber can create processing problems. A need exists for carpet yarns that may be tufted into carpets to provide good carpet body in such a manner that the above problems are avoided.
Softness of hand for a given fibrous material depends upon the denier of the filaments in the yarn, yarn twist, and the fiber cross-section. Smaller denier fibers yield improved softness but may be more costly and difficult to produce. Lower twist increases softness but reduces resistance to wear (appearance loss). The manufacture of carpet yarns is a highly competitive industry under significant price pressures. A need exists for carpet yarns that possess greater softness of hand but that may be produced without increasing costs or reducing appearance retention.
The denier and shape of the fiber cross-section determine the moment of inertia and the covering power of the fiber cross-section. Cross-sectional shapes having high moments of inertia have high covering power but possess less softness of hand. A need exists for carpet yarns that possess a desirable balance of covering power and softness of hand.
For many styles of carpet, yarns having a low luster are required. Fibers having a circular cross-section have the requisite low luster but have poorer covering power than fibers with lobal cross-sections. A need exists for carpet yarns possessing a desirable balance of covering power and low luster.
The color intensity produced by dyeing may vary with the filament cross-section and the manner in which light is reflected and absorbed. A need exists for carpet yarns possessing ease of dyeing to high color intensity.
There is a long history of prior art yarns that had the objectives of improving the properties of carpets by design of the constituent fiber cross-sections. Fibers or filaments having trilobal and tetralobal cross-sections have been widely used for carpet yarns due to their bulk and covering power advantages over fibers having round or ribbon cross-sections. Solid trilobal filaments are described for example in U.S. Pat. No. 2,939,201 to Holland; U.S. Pat. No. 3,097,416 to McKinney, U.S. Pat. No. 3,508,390 to Bagnall et al.; U.S. Pat. No. 4,001,360 to Shah; U.S. Pat. No. 4,492,731 to Bankar et al.; U.S. Pat. No. 5,057,368 to Largman et al.; and U.S. Pat. Nos. 5,108,838 and 5,208,106 to Tung. Hollow trilobal fibers are described for example in U.S. Pat. No. 4,770,938 to Peterson et al.; U.S. Pat. No. 5,322,736 to Boyle; U.S. Pat. No. 5,380,592 to Tung and European Patent 982 414 A1 to Bernaschek. The disclosures of U.S. Pat. Nos. 3,508,390 and 5,322,736 are hereby incorporated herein by reference to the extent not incompatible herewith.
Each of the fibers and carpet yarns cited above represented progress toward the goals to which they were directed. However, none described the specific constructions of the filaments and yarns of this invention and none satisfied all of the needs met by this invention.
This invention relates to: novel filaments for use in carpets, upholstery and other applications; a method and spinneret used for their production; and yarns and carpets manufactured therefrom. The filaments of the invention are solid multi-lobal filaments of complex convex-concave surface contour possessing a low moment of inertia, low luster, and high covering power. One embodiment of this invention, among others, is a filament comprising: a solid cross-section having a modification ratio of about 2.4 to about 5 and having a perimeter comprised of a plurality of lobes that are joined to one another by concave line segments. Upon traversing in one direction completely around the perimeter of the filament cross-section, the position of the center of curvature for the perimeter changes from one side of the perimeter to the other side at least eighteen times.
The filaments of the invention possess superior combinations of low luster, easy dyeing to high color intensity, high body, soft hand and high covering power.
The invention includes as embodiments yarns comprising filaments of the invention and carpets comprising yarns of the invention. The invention also includes as embodiments the spinnerets used to make the filaments of the invention and the method of producing the filaments of the invention.